1. Field of the Invention
The invention relates to the ablation of pathological tissues, such as tumors, or nodules, through a precise local heating. This is done by applying physical energy radiation e.g. by acoustic waves into the targeted tissue, which is converted into heat therein. As soon as the temperature reaches a certain level of about 80° C., tissue is coagulated and a necrosis develops.
2. Description of Related Art
For a non-invasive treatment, in the U.S. Pat. No. 6,379,320 B1 a focused ultrasound source is provided in the tip of an endoscope for radiating radially. The focus spot cannot be adjusted; therefore, the endoscope must be brought close to the region to be treated, which is often not possible.
An endoscope with integrated ultrasound source is disclosed in DE 44 43 947 A1. For generating an ultrasound wave, which is focused at a variable distance, a large number of phased-array transducer elements are provided which are driven by individual oscillators. This requires complex electronics, and the power output of the transducer is limited due to acoustic crosstalk between the individual transducer elements
The US patent application publication US 2003/0004439 A1 discloses and intrabody HIFU (High Intensity Focused Ultrasound) applicator, which uses a plurality of ultrasound transducers mounted on a flexible holder. These transducers are transported by an endoscope into the body, but operated outside of the endoscope. Therefore, a significant amount of space is required within the body, which severely limits the application range of this instrument